(Lit) Add restaurant sample v0.9

[ditman]

Description

This PR builds on top of #1079 and ports the "shell" app to use the v0.9 renderer.

Issues

• Part of: Update all Lit renderer samples to use v0.9 #702

Pre-launch Checklist

• I signed the CLA.
• I read the Contributors Guide.
• I read the Style Guide.
• I have added updates to the CHANGELOG.
• I updated/added relevant documentation.
• My code changes (if any) have tests.

If you need help, consider asking for advice on the discussion board.

[ditman]

(Everything outside "samples" is covered by a separate PR, feel free to ignore those)

[gemini-code-assist]

Code Review

This pull request refactors the A2UI Lit renderer for version 0.9.0, introducing a centralized theming system and migrating components from inline styles to CSS variables. It includes a new v0.9 sample shell and updates to the web_core package to support shared design tokens. Review feedback suggests removing unnecessary placeholder characters in the Divider, adopting declarative style bindings in the Image component, cleaning up unused imports, adding missing type annotations, and consolidating flex-weight logic in the base class to avoid redundancy. Additionally, it was noted that static class names should be used instead of classMap for better performance in the Icon component.

[gemini-code-assist]

The request parameter is missing a type annotation. Adding a type (e.g., any or a more specific interface if available) improves type safety and developer experience in this TypeScript project.

Suggested change

	async #sendAndProcessMessage(request) {
	async #sendAndProcessMessage(request: any) {